Small Form-factor Pluggable (SFP) transceiver modules are relatively small, hot-swappable devices that can be plugged into a variety of host networking equipment. The portions of optical SFP transceiver modules and electrical SFP transceiver modules that are configured to be received inside a host port (“the host port portion”) both conform to the SFP Transceiver Multi-Source Agreement (MSA), which is incorporated herein by reference in its entirety. The SFP Transceiver MSA specifies, among other things, package dimensions for the host port portions of such transceiver modules. Specifically, the Appendix A.A1 of the SFP Transceiver MSA specifies package dimensions for SFP transceiver modules. The conformity of the host port portions of the electrical and optical SFP transceiver modules, with respect to package dimensions and host interface configurations, allows an optical SFP transceiver module to be replaced by an electrical SFP transceiver module without affecting the operation of the host networking equipment. This interchangeability between electrical and optical SFP transceiver modules allows for flexibility in a communications network that includes both electrical and optical cabling.
The dimensional conformity required by the SFP Transceiver MSA creates some limitations, however, for electrical SFP transceiver module design. Specifically, dimensional conformity of the host port portion required by the SFP Transceiver MSA defines a finite volume within which components of the SFP transceiver module can be located. Among the components included in the host port portion of a typical electrical SFP transceiver module are one or more printed circuit boards and multiple magnetic cores. Each magnetic core acts as a transformer and a common-mode choke for electrical data signals passing through the electrical SFP transceiver module. Each magnetic core acts as a transformer by increasing or decreasing the voltage and current of electrical data signals passing through the magnetic core. Each magnetic core acts as a common-mode choke by reducing common mode electrical noise in the electrical data signals passing through the magnetic core.
The printed circuit boards generally include various electronic circuitry and components that provide functionality to the electrical SFP transceiver module. To the extent that relatively more space can be made available on the printed circuit boards, relatively more electronic circuitry and components and functionality can be included within the electrical SFP transceiver module.
In addition, electrical SFP transceiver module designs are continually being modified to enable transceiver operation over ever-larger temperature ranges. In response, the magnetic cores employed within the electrical SFP transceiver modules have correspondingly increased in size. For example, magnetic cores in an electrical SFP transceiver designed to operate within a −40° C. to 85° C. temperature range will generally be relatively larger in size than magnetic cores in an electrical SFP transceiver designed to operate within a 0° C. to 70° C. temperature range. Consequently, where more of the available space within an electrical SFP transceiver module is being utilized by larger magnetic cores, less space is available for the inclusion of desirable electronic components on the printed circuit boards of the electrical SFP transceiver module.
Furthermore, the relative placement of magnetic cores can be critical to transceiver performance. For example, magnetic cores that are positioned too close together in an electrical SFP transceiver module may cause an undesirably high bit error rate (BER) in the electrical SFP transceiver module. Although relatively precise placement of magnetic cores is required in order to achieve an acceptably low BER, the proper placement of magnetic cores within an electrical SFP transceiver module can be difficult due to the limited space within the electrical SFP transceiver module.